Showing posts with label supply. Show all posts
Showing posts with label supply. Show all posts
Sunday, September 21, 2014
Dual Output DC DC Power Supply for AMOLED Displays
This is a dual-output switch mode power supply reference design based on the MAX17116. The part and reference circuit can provide both negative and positive supplies to AMOLED displays. [via]
The MAX17116 includes two current-mode 1.4MHz switch mode power-supply (SMPS) regulators for active-matrix organic light-emitting diode (AMOLED) displays. The positive supply is provided by a step-up regulator with a synchronous rectifier. The negative supply is provided by an inverting regulator with a synchronous rectifier.[Link]
Tuesday, April 30, 2013
Soft Start For Switching Power Supply
Switching power supply whose output voltage is appreciably lower than its input voltage has an interesting property: the current drawn by it is smaller than its output current. However, the input power (UI) is, of course, greater than the output power. There is another aspect that needs to be watched: when the input voltage at switch-on is too low, the regulator will tend to draw the full current. When the supply cannot cope with this, it fails or the fuse blows. It is, therefore, advisable to disable the regulator at switch-on (via the on/off input). until the relevant capacitor has been charged. When the regulator then starts to draw current, the charging current has already dropped to a level which does not overload the voltage source.
Circuit diagram:
Circuit diagram:
Soft Start Circuit For Switching Power Supply
The circuit in the diagram provides an output voltage of 5 V and is supplied by a 24 V source. The regulator need not be disabled until the capacitor is fully charged: when the potential across the capacitor has reached a level of half or more of the input voltage, all is well. This is why the zener diode in the diagram is rated at 15 V. Many regulators produced by National Semiconductor have an integral on/off switch, and this is used in the present circuit. The input is intended for TTL signals, and usually consists of a transistor whose base is accessible externally. This means that a higher switching voltage may be applied via a series resistor: the value of this in the present circuit is 22 kΩ. When the voltage across the capacitor reaches a level of about 17 V, transistor T1 comes on, whereupon the regulator is enabled.
Source: National Semiconductors
Monday, April 8, 2013
Supply Voltage Monitor
A circuit for monitoring supply voltages of ±5 V and ±12 V is readily constructed as shown in the diagram. It is appreciably simpler than the usual monitors that use comparators, and AND gates. The circuit is not intended to indicate the level of the inputs. In normal operation, transistors T1 and T3 must be seen as current sources. The drop across resistors R1 and R2 is 6.3 V (12 –5 –0.7). This means that the current is 6.3mA and this flows through diode D1 when all four voltages are present. However, if for instance, the –5 V line fails, transistor T3 remains on but the base-emitter junction of T2 is no longer biased, so that this transistor is cut off. When this happens, there is no current through D which then goes out.
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Sunday, April 7, 2013
Timer Batterays Supply
One needs that is often emerges at equipments energy by battery was that battery can be killed after one certain time periods. Though circuit timer a lot, but no matter simple to be able to decide power supply allowance after used for several hour/clock. circuit depicted here can did this task by using current only some nanoampere.
View at circuit diagram shows that not many component applied. Switches S1 is nipple " ON", if it is depressed will ration bases rudder current at transistor Darlington T1 which then menghantarkann will to ration equipments is being used. Transistor T2 now will pass also, and acts as breach-block S1 in business is maintaining bases current to T1. Condenser C1 will start filling R4. if strain at R4 shoot until 1, 2V, hence T2 will break. In turn, this thing will kill T1 and hence allowance will be desisted also. The only flowing current is blowby current passing both transistors, but this biggest current only some nanoampere only. for all need, battery allowance will be stopped.
For they hesitating of mentoba " tries and sees" possibly will require more time, but will work good. If required, both replaceable Darlington with separate transistor.
View at circuit diagram shows that not many component applied. Switches S1 is nipple " ON", if it is depressed will ration bases rudder current at transistor Darlington T1 which then menghantarkann will to ration equipments is being used. Transistor T2 now will pass also, and acts as breach-block S1 in business is maintaining bases current to T1. Condenser C1 will start filling R4. if strain at R4 shoot until 1, 2V, hence T2 will break. In turn, this thing will kill T1 and hence allowance will be desisted also. The only flowing current is blowby current passing both transistors, but this biggest current only some nanoampere only. for all need, battery allowance will be stopped.
For they hesitating of mentoba " tries and sees" possibly will require more time, but will work good. If required, both replaceable Darlington with separate transistor.
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